Substituted, unsaturated, bicyclic imides and polymers thereof

ABSTRACT

Imides of the formula I    &lt;IMAGE&gt;  (I)  in which E is allyl or methallyl, R is hydrogen, alkyl, alkenyl, cycloalkyl, aryl, benzyl, alkylene or arylene, and n is 1 or 2, are intermediates for the preparation of crosslinked polymers having excellent physical properties. The polymers can be used, in particular, for the preparation of glass fibre-reinforced and carbon fibre-reinforced plastics and heat-resistant composite materials, and as electrical insulation materials and whirl-sintered powder paints.

This is a divisional of application Ser. No. 693,640, filed on Jan. 22,1985, now U.S. Pat. No. 4,604,437, issued on Aug. 5, 1986.

The invention relates to allyl-substituted or methallyl-substitutedmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximides, to their preparationand to the polymers which can be obtained therefrom by heating.

Maleimides and bismaleimides and also N-allylmonomaleimides are known.

The curing of halogenated, olefinic rubber polymers by means of selectedpolymaleimide compounds, such as N,N'-m-phenylene-bismaleimide, isdescribed in U.S. Pat. No. 3,334,075. These polymaleimides do notcontain any allyl or norbornenyl groups, and the maleimide radicals donot carry any substituents.

Resin-forming compositions containing maleimide or bismaleimidederivatives, such as N-phenylmaleimide andmethylene-bis-(N-phenylmaleimide), are known from British Pat. No.1,277,790. None of these compounds contains norbornenyl or allyl groups.

A process for the preparation of bismaleimides by reacting a bismaleamicacid with the anhydride of a lower carboxylic acid in the presence of atertiary amine, an organic solvent and a nickel catalyst is described inU.S. Pat. No. 3,839,358. A process for the preparation of monomaleimidesand bismaleimides containing aliphatic substituents on the nitrogen atomis known from U.S. Pat. No. 4,229,351. The preparation of compoundscontaining allyl-substituted and methyl-substituted norbornenyl groupsis not described or suggested either in the former or in the latterpatent.

U.S. Pat. No. 3,450,711 relates to bisimide compounds prepared byreacting endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride(=5-norbornene-2,3-dicarboxylic anhydride) with selected organicdiamines. These bisimides do not contain either methyl or allylsubstituents in the imide radical and are distinguished from the presentcompounds both by their structure and by their chemical reactivity. Thecompounds according to this U.S. patent are used as intermediates in thepreparation of epoxide compounds.

It is also known that it is possible to prepare polyimide oligomerswhich are used as adhesives by addition of3,3',4,4'-benzophenonetetracarboxylic dianhydride ontodiaminodiphenylmethane in the presence of various compounds capable ofcausing crosslinking and end group masking, such as chlorinated orunchlorinated 5-norbornenecarboxylic anhydride and 5-vinylphthalicanhydride [cf., for example, Polym. Eng. Sci., 22, 9-14 (1982)]. Thesepolyimide oligomers do not contain any allyl groups.

Silanes prepared from imide intermediates including, for example,N-allyl-2,3-dimethylmaleimide, are described in U.S. Pat. No. 4,271,074.The monomers according to the invention do not contain any norbornenylgroup which is substituted by an allyl group and a methyl group, and aretherefore entirely different in structure and are not suggested by thispatent.

The preparation of the starting materials for the compounds according tothe invention is described in U.S. Pat. No. 3,105,839.

The allyl-substituted or methallyl-substitutedmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximides according to theinvention are valuable starting materials for polymers which haveexcellent properties. They are characterised by formula I below:##STR2## in which E is allyl or methallyl and n is 1 or 2 and, if n is1, R is hydrogen, alkyl having 1-12 C atoms, alkenyl having 3-6 C atoms,cycloalkyl having 5-8 C atoms, aryl having 6-10 C atoms or benzyl, or,if n is 2, R is --C_(m) H_(2m) -- in which m is 2-20, arylene having6-10 C atoms or a group of the formula II ##STR3## in which T ismethylene, isopropylidene, CO, O, S or SO₂.

E is preferably the allyl group.

R can be a linear or branched-chain alkyl group having 1-12 C atoms,such as methyl, ethyl, isopropyl, n-butyl, isopentyl, n-hexyl,2-ethylhexyl, n-decyl and n-dodecyl, preferably alkyl having 1-8 Catoms.

R can also be a linear or branched-chain alkenyl group having 3-6 Catoms, such as allyl, methallyl, 2-butenyl and 3-hexenyl, preferablyallyl.

As a cycloalkyl group, R can be a cyclopentyl, cyclohexyl, cycloheptylor cyclooctyl group, preferably cyclohexyl.

As an aryl group, R can be unsubstituted phenyl or a phenyl group whichis substituted by one or two methyl groups, such as tolyl or xylyl, ornaphthyl too. The phenyl group is preferred. As a group --C_(m) H_(2m)--, R can be a linear or branched radical, such as ethylene, propylene,trimethylene, tetramethylene, hexamethylene, octamethylene anddodecamethylene. As a group of the formula II, R is preferably attachedto the N atoms in the 4,4'-position.

R is preferably a group --(CH₂)_(m) -- in which m is 2 to 12.

As an arylene group having 6-10 C atoms, R can be, for example, anm-phenylene, p-phenylene, 1,3-naphthylene, 1,4-naphthylene,1,5-naphthylene or 2,6-naphthylene group.

If R is a group of the formula II, T is preferably the methylene group,O or SO₂.

Preferred compounds of the formula I are those in which, if n is 1, R ishydrogen, alkyl having 1-8 C atoms, cyclohexyl, allyl or phenyl, or, ifn is 2, R is --(CH₂)₆ -- or a group of the formula II in which T is themethylene group or SO₂.

Compounds of the formula I which are particularly preferred are those inwhich n is the number 2 and R is ##STR4##

Compounds of the formula I which are very particularly preferred arethose in which E is the allyl group and, if n is 1, R is allyl, or, if nis 2, R is --(CH₂)₆ -- or ##STR5##

The imides according to the invention can be prepared in a manner knownper se, for example by reacting an anhydride of the formula III ##STR6##with a compound of the formula IV

    (H.sub.2 N).sub.n R                                        (IV)

in which E, R and n are as defined under formula I, at an elevatedtemperature and with removal by distillation of the water formed in thereaction. If the compounds of the formula IV are ammonia or low-boilingmonoamines, an excess of these reactants is advisable. It isadvantageous to employ diamines in a stoichiometric ratio. The reactioncan be carried out without a solvent or in the presence of an inertsolvent which can be used for the azeotropic solvent of the water(entraining agent). The temperature of the reaction can be between 100°and 250° C. The imides of the formula I are preferably prepared in themelt under a pressure of not more than 4,500 Pa and at temperaturesbetween 130° and 220° C., in particular 180° and 220° C.

As already mentioned, the starting materials of the formula III can beprepared in accordance with the process described in U.S. Pat. No.3,105,839 by reacting sodium methylcyclopentadienide with an allyl ormethallyl halide, followed by a Diels-Alder reaction with maleicanhydride. Although it is stated in the U.S. Patent that the allyl groupis attached in the 7-position of the bicyclic system, recentinvestigations show that an isomeric mixture is formed in respect of theposition of the allyl group (in the 1-position and the 6-position) andalso in respect of the endo-configuration and exo-configuration of theanhydride moiety. Hitherto it has only been possible to isolate theisomeric components by preparative gas chromatography.

The monoamines or diamines of the formula IV which are used are known orcan be prepared by processes known per se.

The compounds according to the invention are liquid, or low-meltingsolid substances which can be polymerised to give solid products havinghigh glass transition points and good resistance to heat and water.These products can be used for many purposes, for example as castingresins or adhesives and, in particular, for the preparation of glassfibre-reinforced or carbon fibre-reinforced plastics and heat-resistantcomposite materials, and as electrical insulating materials andwhirl-sintered powder paints.

The compounds according to the invention can be used and polymerisedwithout further treatment, or they can first be dissolved in an organicsolvent, such as toluene, xylene, methyl ethyl ketone, ethylene glycolmonoalkyl and dialkyl ethers having 1-4 C atoms in the alkyl groups or asimilar solvent, customary in the paint industry. Solutions of this typecan be used as impregnating agents or coating agents or as a form ofdispatch to the consumer.

The compounds, according to the invention, of the formula I can bereacted to give novel polymers, and, surprisingly, the methylsubstituent hardly impairs the capacity of the allylnorbornene systemfor polymerisation. Accordingly, the invention also relates to the novelpolymers which can be obtained by heating an imide of the formula I at atemperature between 180° and 300° C., preferably between 200° and 250°C., for 6 to 60 hours. In this respect, what has been stated aboveapplies in respect of the preferred meanings of E, R and n. Polymerswhich are particularly preferred are those which can be obtained byheating an imide of the formula I in which n is the number 2 and R isthe group ##STR7## at 240° to 250° C. for 6-24 hours.

It is, of course, possible to add inert and stable substances, such asfillers, pigments, dyes and other additives, to the imides of theformula I before they are polymerised to give crosslinked structures.

PREPARATION EXAMPLES EXAMPLE 1Allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide

A mixture of 30 g ofallylmethylbicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic anhydride,prepared in accordance with Example 2 of U.S. Pat. No. 3,105,839, and10.2 g of 25% aqueous ammonia solution is heated at 100°-108° C. for 2.5hours, with stirring and reflux cooling. According to a gaschromatogram, this gives a mixture of 12 isomers having varyingpositions for the allyl group and the methyl group in the 1-, 4-, 5- and6-positions in the bicycloheptene ring, and also exo-anhydrides andendo-anhydrides. Since this mixture of isomers cannot be separated byfractional distillation, it is used for further purposes as such. Wateris then removed by distillation, excess ammonia is expelled and theimide is rectified at 140°-145° C. and 2.0 Pa.

21.5 g of a mixture of isomers ofallylmethylbicyclo[2.2.1]hept-5-enedicarboxylic acid 2,3-imide areobtained, corresponding to a yield of 71.3% of theory. The imide is ayellow syrup and has a viscosity of 96.18 mPa.s at 80° C.

    ______________________________________                                        Analysis         % C       % H    % N                                         ______________________________________                                        calculated for C.sub.13 H.sub.15 NO.sub.2                                                      71.87     6.96   6.45                                        found            71.41     6.94   6.42                                        ______________________________________                                    

IR spectrum: 1639.2 cm⁻¹ cyclic double bond, 1653.4 cm⁻¹ allyl group,1708.9 cm⁻¹ carbonyl group, 1778.0 cm⁻¹ carbonyl in the cyclic imide,3210.3 cm⁻¹ NH vibration.

Polymerisation for 48 hours at 250° C. gives a solid having a glasstransition temperature (GTT) of 125° C. The IR spectrum contains noabsorption bands for ##STR8## double bonds (1639.2 and 1653.4 cm⁻¹).

EXAMPLE 2 Allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acidN-allylimide

A mixture of 30 g of allylmethylbicyclo[2.2.1]hept-5-ene2,3-dicarboxylicanhydride and 9.41 g of allylamine is heated at reflux temperature for 2hours, water is removed by distillation, and the product is rectified at119°-127° C. and 2.66 Pa. This gives 30.24 g (85.5% of theory) of a paleyellow oil having the following characteristic data: n_(D) ²⁰ =1.5202,η₂₅ =0.135 Pa.s.

    ______________________________________                                        Analysis         % C       % H    % N                                         ______________________________________                                        calculated for C.sub.16 H.sub.19 NO.sub.2                                                      74.68     7.84   5.44                                        found            74.66     7.55   5.22                                        ______________________________________                                    

Polymerisation for 48 hours at 250° C. gives a solid having a GTT>250°C. and an IR spectrum which shows no ##STR9## absorption frequencies(1639.2 and 1653.4 cm⁻¹).

EXAMPLE 3 Allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acidN-(2-ethylhexyl)-imide

30 g of anhydride are reacted with 21.3 g of 2-ethylhexylamine asdescribed in Example 2 above. Distillation at 3.3 Pa gives, between 149°and 162° C., 40.74 g of a yellow oil (90% of theory) having a refractiveindex n_(D) ²⁰ =1.5090 and a viscosity of 0.306 Pa.s at 25° C.

    ______________________________________                                        Analysis         % C       % H    % N                                         ______________________________________                                        calculated for C.sub.21 H.sub.31 NO.sub.2                                                      76.55     9.48   4.52                                        found            76.32     9.48   4.16                                        ______________________________________                                    

Polymerisation for 40 hours at 250° C. gives a solid having a GTT of128° C. The IR bands for double bonds at 1639.2 and 1653.4 cm⁻¹ can nolonger be detected.

EXAMPLE 4 Allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acidN-phenylimide

30 g of anhydride are reacted with 15.4 g of aniline as described inExample 2. The anilide is distilled between 161° and 165° C. at 6.65 Pato give 23.2 g (57.5% of theory) of a viscous liquid having a viscosityof 4.2 Pa.s at 40° C. and a refractive index n_(D) ²⁰ =1.5647 at 20° C.

    ______________________________________                                        Analysis         % C       % H    % N                                         ______________________________________                                        calculated for C.sub.19 H.sub.19 NO.sub.2                                                      77.79     6.53   4.77                                        found            77.92     6.46   4.68                                        ______________________________________                                    

Polymerisation for 48 hours at 250° C. gives a solid having a GTT of132.5° C. and an IR spectrum which has no ##STR10## absorptionfrequencies (1639.2 and 1653.4 cm⁻¹).

EXAMPLE 5N,N'-Hexamethylene-bis-(allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)

300 g of allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydrideare taken and heated to 130° C., and 79.9 g of melted hexamethylenediamine are added dropwise, with stirring. Water is removed bydistillation, the temperature is raised to 180° C. and the pressure isreduced to 53 Pa. 180° C. and 53 Pa are maintained for 15 minutes. Thisgives 345 g (97% of theory) of a brown, viscous resin having a viscosityof 1.356 Pa.s at 80° C.

    ______________________________________                                        Analysis         % C       % H    % N                                         ______________________________________                                        calculated for C.sub.32 H.sub.40 N.sub.2 O.sub.4                                               74.39     7.80   5.42                                        found            73.82     7.74   5.47                                        ______________________________________                                    

EXAMPLE 6Bis-[4-(allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximidophenyl)]-methane##STR11##

300 g of anhydride and 136.2 g of 4,4'-diaminodiphenylmethane arereacted as described in Example 5. This gives 403.2 g (98.0% of theory)of a dark brown solid resin having a glass transition temperature of 66°C.

    ______________________________________                                        Analysis:         % C       % H    % N                                        ______________________________________                                        calculated for C.sub.39 H.sub.38 N.sub.2 O.sub.4 :                                              78.24     6.40   4.68                                       found:            78.41     6.49   4.68                                       ______________________________________                                    

EXAMPLE 7Bis-[4-(methallylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximidophenyl)]sulfone##STR12##

124.15 g of 4,4'-diaminodiphenyl sulfone and 232 g ofmethallylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride areheated to 180° C., and the pressure is reduced in stages to 25 Pa. After90 minutes at 180° C. and 25 Pa, 319.55 g of a brown solid resin havinga glass transition temperature of 87° C. are obtained.

    ______________________________________                                        Analysis:        % C     % H     % N   % S                                    ______________________________________                                        calculated for C.sub.40 H.sub.40 N.sub.2 O.sub.6 S:                                            70.98   5.96    4.14  4.74                                   found:           69.98   5.91    4.35  4.98                                   ______________________________________                                    

The anhydride is prepared analogously to Examples 1 and 2 of U.S. Pat.No. 3,105,839. 994 g of methallyl chloride are used instead of 840 g ofallyl chloride. The anhydride, which has not hitherto been described inthe literature, distills at 125°-140° C. and 25 Pa, and has n_(D) ²⁰=1.508 and a viscosity of 195 mPa.s.

EXAMPLE 8Bis-[4-(methallylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximidophenyl)]-methane##STR13##

116 g of methallylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylicanhydride and 49.5 g of 4,4'-diaminodiphenylmethane are heated to 200°C., with stirring, in an atmosphere of N₂. 9 cm³ of water are distilledoff. In the course of 35 minutes at 200° C. the glass transitiontemperature rises from 67.5° to 78.5° C. Yield 155 g (99% of theory).

    ______________________________________                                        Analysis:         % C       % H    % N                                        ______________________________________                                        calculated for C.sub.41 H.sub.42 N.sub.2 O.sub.4 :                                              78.57     6.75   4.47                                       found:            77.41     6.71   4.39                                       ______________________________________                                    

EXAMPLE 9 Allylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acidN-cyclohexylimide

A mixture of 20 g ofallylmethylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride and 9.09g of cyclohexylamine is heated at 135° C. for 3 hours, and the productis then distilled in vacuo. 16 g of a yellow, viscous oil distill overbetween 128° and 138° C. at 2.5 Pa, corresponding to a yield of 58.2%.

    ______________________________________                                        Analysis:         % C       % H    % N                                        ______________________________________                                        calculated for C.sub.19 H.sub.25 NO.sub.2 :                                                     76.25     8.36   4.68                                       found:            76.46     8.52   4.38                                       ______________________________________                                    

Thermal polymerisation for 48 hours at 250° C. gives a solid resinhaving a glass transition temperature of 72.5° C.

The molecule of the compounds according to the invention contains two ormore olefinic double bonds which make them capable of polymerisation.Crosslinked polymers having valuable physical properties are obtained onheating, cf. Examples 1-4.

USE EXAMPLES EXAMPLE I

The imide prepared in accordance with Example 5 is poured, in the formof a hot, low-viscosity melt, into a steel mould measuring 12×12×0.4 cmand cured for 3 hours at 200°, 3 hours at 225° and 12 hours at 250° C.After cooling, test rods are cut from the sheet. The followingproperties are measured on these:

    ______________________________________                                        Flexural strength as specified in DIN 53,452:                                                         81.5    N/mm.sup.2                                    Deflection as specified in DIN 53,452:                                                                5.2     mm                                            Impact strength as specified in DIN 53,455:                                                           13.2    kJ/m.sup.2                                    Glass transition temperature                                                                          201°                                                                           C.                                            (TA 2000 made by Mettler)                                                     Water absorption (1 hour/100° C.)                                                              0.48%                                                 Tensile shear strength on                                                                             9.9     N/mm.sup.2                                    Anticorodal as specified in DIN 53,283                                        ______________________________________                                    

EXAMPLE II

The imide resin prepared in accordance with Example 6 is melted, pouredinto a steel mould measuring 12×12×0.4 cm and cured for 3 hours at 200°,3 hours at 225° and 12 hours at 250° C. After cooling, the plate is cutinto test rods, on which the following properties are measured:

    ______________________________________                                        Flexural strength as specified in DIN 53,452:                                                         95      N/mm.sup.2                                    Deflection as specified in DIN 53,452:                                                                4.5     mm                                            Impact strength as specified in DIN 53,455:                                                           9.5     kJ/m.sup.2                                    Glass transition temperature                                                                          192°                                                                           C.                                            (TA 2000 made by Mettler)                                                     Water absorption (1 hour/100° C.):                                                             0.35%                                                 Tensile shear strength on                                                                             7.6     N/mm.sup.2                                    Anticorodal as specified in DIN 53,283:                                       ______________________________________                                    

The following properties were measured on a test sheet (12×12×0.2 cm):

    ______________________________________                                        Volume resistivity (DIN 53,482)                                                                      5.0 × 10.sup.16 cm                               Dissipation factor (DIN 53,483)                                                                      0.25%                                                  Dielectric constant (DIN 53,483)                                                                     3.2                                                    ______________________________________                                    

EXAMPLE III

After curing for 24 hours at 250° C., the resin prepared in accordancewith Example 7 has a glass transition temperature >250° C. and a tensileshear strength on Anticorodal as specified in DIN No. 53,283 of9.5N/mm².

What is claimed is:
 1. An imide of the formula I ##STR14## in which E isallyl or methallyl and n is 1 or 2 and, when n is 1, R is hydrogen,alkyl having 1-12 C atoms, alkenyl having 3-6 C atoms, cycloalkyl having5-8 C atoms, aryl having 6-10 C atoms or benzyl, or, when n is 2, R is--C_(m) H_(2m) -- in which m is 2-20, arylene having 6-10 C atoms or agroup of the formula II ##STR15## in which T is methylene,isopropylidene, CO, O, S or SO₂.
 2. An imide of the formula I, accordingto claim 1, in which E is the allyl group.
 3. An imide of the formula I,according to claim 1, in which, when n is 1, R is hydrogen, alkyl having1-8 C atoms, cyclohexyl, allyl or phenyl, or, when n is 2, R is --(CH₂)₆-- or a group of the formula II ##STR16## in which T is the methylenegroup or SO₂.
 4. An imide of the formula I, according to claim 1, inwhich n is the number 2 and R is --(CH₂)₆ --, ##STR17##
 5. An imide ofthe formula I, according to claim 1, in which E is the allyl group and,when n is 1, R is allyl or, when n is 2, R is --(CH₂)₆ -- or ##STR18##6. An imide of the formula I, according to claim 1, in which E is allyl,n is 1 and R is hydrogen.
 7. An imide of the formula I, according toclaim 1, in which E is allyl, n is 1 and R is allyl.
 8. An imide of theformula I, according to claim 1, in which E is allyl, n is 1 and R is2-ethylhexyl.
 9. An imide of the formula I, according to claim 1, inwhich E is allyl, n is 1 and R is phenyl.
 10. An imide of the formula I,according to claim 1, in which E is allyl, n is 2 and R is --(CH₂)₆ --.11. An imide of the formula I, according to claim 1, in which E isallyl, n is 2 and R is ##STR19##
 12. An imide of the formula I,according to claim 1, in which E is methallyl, n is 2 and R is ##STR20##13. An imide of the formula I, according to claim 1, in which E ismethallyl, n is 2 and R is ##STR21##
 14. The imide of the formula I,according to claim 1, in which E is allyl, n is 1 and R is cyclohexyl.